In the present work Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy is applied to study the adsorption of NOx at 300-500 °C in different atmospheres on gadolinium doped ceria (CGO), an important material in electrodes investigated for electrochemical NOx removal. Furthermore, the effect on the NOx adsorption when adding K2O or BaO to the CGO is investigated. The DRIFT study shows mainly the presence of nitrate species at 500 °C, while at lower temperature a diversity of adsorbed NOx species exists on the CGO. Presence of O2 is shown to have a strong effect on the adsorption of NO, but no effect on the adsorption of NO2. Addition of K2O and BaO dramatically affects the NOx adsorption and the results also show that the adsorbed NOx species are mobile and capable of changing adsorption state in the investigated temperature range.